The objectives of this research project are to continue our studies on the effect of cholera enterotoxin on adrenal tumor cells in tissue culture. The toxin is capbale of inducing cellular morphological changes and steroidogenesis in these cells and we are interested in defining the toxin's molecular mechanisms of action. Our comprehensive studies will include analyses of 1) any ultrastructural or immunochemical changes occurring in cell surface elements or intracellular organelles as a result of cellular exposure to cholera enterotoxin, 2) the metabolic effects of the toxin (including alterations in macromolecular synthetic processes), and 3) the effects of the toxin on membrane permeabilities and other membrane functions, and will especially focus on the molecular events occurring between the initial binding of the toxin to the cell and the subsequent stimulation of membrane adenyl-cyclase. Electron microscopic techniques as well as immunochemical and physicochemical methods will be used in the course of these studies as will be radioisotopically-labelled toxin and metabolic precursors. Of special interest as well be the effects of the toxin, or fragments thereof, on whole cell and broken cell preparations, and an attempt made to isolate and identify the membrane and/or cytoplasmic components necessary for the toxin's actions. As choleragenoid, the naturally occurring toxoid of cholera enterotoxin, has effects on this adrenal cell model system differing from those on intestine and other model systems, it will be important to more precisely define these effects of the toxoid on adrenal cells and how they compare with those of the toxin. BIBLIOGRAPHIC REFERENCES: Donata, S.T. and Viner, J.P.: Inhibition of the steroidogenic effects of cholera and heat-labile E. coli enterotoxins by GM1 ganglioside - Evidence for a similar receptor site for the two toxins. Infect. Immun. 11:982-985, 1975. Donata, S.T.: Interactions of choleragenoid and GM1 ganglioside with chlorea and E. coli enterotoxins in adrenal cultured cells. J. Infect. Dis. 133:S115-S119, 1976.